城市下垫面对渤海湾海风锋特征影响的一次数值试验  

A Numerical Study of the Urban Underlying Surface Effect on the Characteristics of a Sea Breeze Front in the Bohai Bay Region

作　　者：梁钊明[1] 高守亭[2] 王东海[1] 王彦[3] 

机构地区：[1]中国气象科学研究院灾害天气国家重点实验室,北京100081 [2]中国科学院大气物理研究所云降水物理与强风暴实验室,北京100029 [3]天津市气象台,天津300074

出　　处：《大气科学》2013年第5期1013-1024,共12页Chinese Journal of Atmospheric Sciences

基　　金：国家自然科学基金资助项目41075043;国家科技支撑计划2008BAC37B01;公益性行业(气象)科研专项GYHY201306009-2

摘　　要：海风锋与沿海强对流天气密切相关,而城市化发展对沿海地区下垫面的改变会对海风锋特征产生影响。鉴于此,本文利用耦合了新一代城市物理方案UCP-BEM(Urban Canopy Parameterization-Building Energy Model)的WRF(Weather Research and Forecasting)模式开展数值试验分析了城市下垫面对渤海湾海风锋特征的影响。结果显示:城市下垫面高粗糙度对低层海风风速的明显削弱造成海风锋往内陆推进距离稍减,低层辐合和上升运动减弱;城市下垫面较大的向上感热通量和较小的向上水汽通量以及高粗糙度对海风的削弱的共同作用造成冷湿海风对低层大气的降温和增湿幅度减弱;高粗糙度的城市下垫面对海风环流的摩擦力效应使得海风得到抬升,这导致了冷湿海风对低层大气的降温和增湿的垂直范围得到提升;受这些结果影响,海风锋背后低层有效位能减小,但垂直分布范围扩大,从而造成对流抑制高值区抬升,同时海风锋背后的静力不稳定区变厚,其上面的动力不稳定区则变薄,但不稳定区总厚度基本不变。Sea breeze fronts are closely related to the severe convective weather that occurs in coastal regions. Changes in the underlying surface of the coastal region, caused by urbanization, influence the characteristics of the sea breeze front. We applied the WRF （Weather Research and Forecasting） model, coupled with a new generation urban physics scheme, the UCP-BEM （Urban Canopy Parameterization-Building Energy model）, to study the effects of urban underlying surfaces on sea breeze front characteristics in the Bohai Bay region. The results showed that the low-level sea breeze was weakened noticeably because of the roughness of the urban underlying surface, leading to decreases in low-level convergence, upward motion, and the inland distance of the sea breeze front. The combination of larger upward sensible heat flux, smaller upward moisture flux, and weaker sea breeze, caused by the thermal and dynamic properties of theurban underlying surface, inhibited the cooling and moistening of the low-level atmosphere from the relatively cool and moist sea breeze. The frictional force effect of the urban underlying surface on sea breeze circulation resulted in the lifting of the sea breeze, expanding the vertical atmospheric cooling and moistening range. The available convective potential energy behind the sea breeze front decreased correspondingly, but its vertical distribution expanded, leading to the uplifting of the convective inhibition center. Moreover, the static instability zone thickened while the dynamic instability zone above it thinned, but the thickness of the whole instability zone remained constant.

关 键 词：城市下垫面 海风锋 数值试验 

分 类 号：P445[天文地球—大气科学及气象学]